Sounds like a speed of execution issue to me, but I cannot remember if the error I typically get says 'cannot find the file specified'.
Take a look at this Support Article: http://portal.blueprism.com/customer-support/support-center#/path/1137420332If that article doesn't solve the issue and this is something that only happens randomly, then I would say something is happening too fast. What's happening in Step 1 of your Navigate Stage 'Input Name'? And do you have a conditional wait before that navigate stage to ensure the element you need is loaded and that the whole webpage is loaded? If you're not already using it, try using 'Parent Document Loaded' in the conditional wait as well since that will ensure the entire page has finished loading before allowing the flow to continue.
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Dave Morris
Cano Ai
Atlanta, GA
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Dave Morris, 3Ci at Southern Company